Non-planar gate thin film transistor

ABSTRACT

Embodiments of the present disclosure describe a non-planar gate thin film transistor. An integrated circuit may include a plurality of layers formed on a substrate, and the plurality of layers may include a first one of a source or drain, an inter-layer dielectric (ILD) formed on the first one of the source or drain, and a second one of the source or drain formed on the ILD. A semiconductive layer may be formed on a sidewall of the plurality of layers. A gate dielectric layer formed on the semiconductive layer, and a gate may be in contact with the gate dielectric layer.

FIELD

Embodiments of the present disclosure generally relate to the field ofintegrated circuits, and more particularly, to a non-planar gate thinfilm transistor.

BACKGROUND

A thin-film transistor (TFT) is a field-effect transistor that includesa thin film of a semiconductive material, a dielectric layer, and metalcontacts over a supporting substrate (which may be non-conductive orsemiconductive). The thin film of semiconductive material forms anactive layer (e.g., a conductive channel) of the TFT. TFTs differ fromother transistors, in which a semiconductor substrate, e.g., a siliconwafer, forms an active channel of the transistor. A TFT may behorizontally placed, e.g., in a planar TFT a semiconductive material maybe formed on a substrate, and a gate dielectric and gate may be formedabove the semiconductive material.

In some horizontally placed TFTs, a width of the transistor is increasedto address a problem of limited drive current and the correspondinglimited performance. However, increasing transistor width utilizeslayout area and may not be acceptable for some applications, where ahigh density of packing is desired.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments will be readily understood by the following detaileddescription in conjunction with the accompanying drawings. To facilitatethis description, like reference numerals designate like structuralelements. Embodiments are illustrated by way of example and not by wayof limitation in the figures of the accompanying drawings.

FIG. 1 schematically illustrates a top view of an example die in waferform and in singulated form, in accordance with some embodiments.

FIG. 2 schematically illustrates a cross-section side view of anintegrated circuit (IC) assembly, in accordance with some embodiments.

FIG. 3 schematically illustrates a cross-section side view of anintegrated circuit including a non-planar gate thin film transistor, inaccordance with some embodiments.

FIG. 4 schematically illustrates a top view of the hole, a source, and adrain for another integrated circuit including a non-planar gate thinfilm transistor, in accordance with some embodiments.

FIGS. 5-8 schematically illustrate cross-section side views of theformation of an integrated circuit that utilizes the hole, source, anddrain of FIG. 4, in accordance with some embodiments.

FIG. 9 is a flow diagram that illustrates a process for forming anintegrated circuit including a non-planar gate thin film transistor, inaccordance with some embodiments.

FIG. 10 schematically illustrates a cross-section side view of anon-planar gate thin film transistor based integrated circuit in aconfiguration for a programmable drive, in accordance with someembodiments.

FIG. 11 schematically illustrates an example system that may include anIC device as described herein, in accordance with some embodiments.

DETAILED DESCRIPTION

Embodiments of the present disclosure describe a non-planar gate thinfilm transistor. An integrated circuit may include a plurality of layersformed on a substrate, and the plurality of layers may include a firstone of a source or drain, an inter-layer dielectric (ILD) formed on thefirst one of the source or drain, and a second one of the source ordrain formed on the ILD. A semiconductive layer may be formed on asidewall of the plurality of layers. A gate dielectric layer formed onthe semiconductive layer, and a gate may be in contact with the gatedielectric layer.

In the following detailed description, reference is made to theaccompanying drawings which form a part hereof, wherein like numeralsdesignate like parts throughout, and in which is shown by way ofillustration embodiments in which the subject matter of the presentdisclosure may be practiced. It is to be understood that otherembodiments may be utilized and structural or logical changes may bemade without departing from the scope of the present disclosure.Therefore, the following detailed description is not to be taken in alimiting sense, and the scope of embodiments is defined by the appendedclaims and their equivalents.

For the purposes of the present disclosure, the phrase “A and/or B”means (A), (B), or (A and B). For the purposes of the presentdisclosure, the phrase “A, B, and/or C” means (A), (B), (C), (A and B),(A and C), (B and C), or (A, B and C).

The description may use perspective-based descriptions such astop/bottom, side, over/under, and the like. Such descriptions are merelyused to facilitate the discussion and are not intended to restrict theapplication of embodiments described herein to any particularorientation.

The description may use the phrases “in an embodiment,” or “inembodiments,” which may each refer to one or more of the same ordifferent embodiments. Furthermore, the terms “comprising,” “including,”“having,” and the like, as used with respect to embodiments of thepresent disclosure, are synonymous.

The term “coupled with,” along with its derivatives, may be used herein.“Coupled” may mean one or more of the following. “Coupled” may mean thattwo or more elements are in direct physical or electrical contact.However, “coupled” may also mean that two or more elements indirectlycontact each other, but yet still cooperate or interact with each other,and may mean that one or more other elements are coupled or connectedbetween the elements that are said to be coupled with each other. Theterm “directly coupled” may mean that two or more elements are in directcontact.

In various embodiments, the phrase “a first feature formed, deposited,or otherwise disposed on a second feature” may mean that the firstfeature is formed, deposited, or disposed over the second feature, andat least a part of the first feature may be in direct contact (e.g.,direct physical and/or electrical contact) or indirect contact (e.g.,having one or more other features between the first feature and thesecond feature) with at least a part of the second feature.

As used herein, the term “circuitry” may refer to, be part of, orinclude an Application Specific Integrated Circuit (ASIC), an electroniccircuit, a processor (shared, dedicated, or group) and/or memory(shared, dedicated, or group) that execute one or more software orfirmware programs, a combinational logic circuit, and/or other suitablecomponents that provide the described functionality.

FIG. 1 schematically illustrates a top view of an example die 102 inwafer form 10 and in singulated form 100, in accordance with someembodiments. In some embodiments, the die 102 may be one of a pluralityof dies (e.g., dies 102, 103 a, 103 b) of a wafer 11 composed ofsemiconductor material such as, for example, silicon or other suitablematerial. The plurality of dies may be formed on a surface of the wafer11. Each of the dies may be a repeating unit of a semiconductor productthat may include one or more active circuit devices that may be formedFEOL (front end of line), which may be underneath one or more non-planargate thin film transistors that may be formed BEOL (back end of line).The one or more transistors formed BEOL may include a transistor formedusing process 900 (FIG. 9) or some other process described herein withreference to FIGS. 3-10.

The die 102 may include circuitry having transistor structures 104 suchas, for example, one or more channel bodies (e.g., fin structures,nanowires, planar bodies, etc.) that provide a channel pathway formobile charge carriers of one or more transistor devices or source/drainregions. Transistor electrode assemblies (e.g., terminal contacts) maybe formed on and coupled with the one or more transistor structures 104to route electrical energy to or from the transistor structures 104. Forexample, terminal contacts may be electrically coupled with a channelbody to provide a gate electrode for delivery of a threshold voltageand/or a source/drain current to provide mobile charge carriers foroperation of a transistor device. Although the transistor structures 104are depicted in rows that traverse a substantial portion of the die 102in FIG. 1 for the sake of simplicity, it is to be understood that thetransistor structures 104 may be configured in any of a wide variety ofother suitable arrangements on the die 102 in other embodiments,including, for example, vertical and horizontal features having muchsmaller dimensions than depicted.

After a fabrication process of the semiconductor product embodied in thedies is complete, the wafer 11 may undergo a singulation process inwhich each of the dies (e.g., die 102) is separated from one another toprovide discrete “chips” of the semiconductor product. The wafer 11 maybe any of a variety of sizes. In some embodiments, the wafer 11 has adiameter ranging from about 25.4 mm to about 450 mm. The wafer 11 mayinclude other sizes and/or other shapes in other embodiments. Accordingto various embodiments, the transistor structures 104 may be disposed ona semiconductor substrate in wafer form 10 or singulated form 100. Thetransistor structures 104 described herein may be incorporated in a die102 for logic or memory, or combinations thereof. In some embodiments,the transistor structures 104 may be part of a system-on-chip (SoC)assembly.

FIG. 2 schematically illustrates a cross-section side view of an ICassembly 200, in accordance with some embodiments. In some embodiments,the IC assembly 200 may include one or more dies (hereinafter “die 102”)electrically and/or physically coupled with a package substrate 121. Insome embodiments, the package substrate 121 may be electrically coupledwith a circuit board 122, as can be seen. In some embodiments, an ICassembly 200 may include one or more of the die 102, package substrate121 and/or circuit board 122, according to various embodiments.Embodiments described herein for an IC structure may be implemented inany suitable IC device according to various embodiments.

The die 102 may represent a discrete product made from a semiconductormaterial (e.g., silicon) using semiconductor fabrication techniques suchas thin film deposition, lithography, etching and the like used inconnection with forming CMOS devices. In some embodiments, the die 102may be, include, or be a part of a processor, memory, SoC or ASIC. Insome embodiments, an electrically insulative material such as, forexample, molding compound or underfill material (not shown) mayencapsulate at least a portion of the die 102 and/or die-levelinterconnect structures 106.

The die 102 can be attached to the package substrate 121 according to awide variety of suitable configurations including, for example, beingdirectly coupled with the package substrate 121 in a flip-chipconfiguration, as depicted. In the flip-chip configuration, an activeside, S1, of the die 102 including circuitry is attached to a surface ofthe package substrate 121 using die-level interconnect structures 106such as bumps, pillars, or other suitable structures that may alsoelectrically couple the die 102 with the package substrate 121. Theactive side S1 of the die 102 may include active devices such as, forexample, transistor devices. An inactive side, S2, may be disposedopposite to the active side S1, as can be seen.

The die 102 may generally include a semiconductor substrate 102 a, oneor more device layers (hereinafter “device layer 102 b”) and one or moreinterconnect layers (hereinafter “interconnect layer 102 c”). Thesemiconductor substrate 102 a may be substantially composed of a bulksemiconductor material such as, for example silicon, in someembodiments.

The device layer 102 b may represent a region where active devices suchas transistor devices are formed on the semiconductor substrate. Thedevice layer 102 b may include, for example, transistor structures suchas channel bodies and/or source/drain regions of transistor devices. Theinterconnect layer 102 c may include interconnect structures that areconfigured to route electrical signals to or from the active devices inthe device layer 102 b. For example, the interconnect layer 102 c mayinclude horizontal lines (e.g., trenches) and/or vertical plugs (e.g.,vias) or other suitable features to provide electrical routing and/orcontacts.

In some embodiments, the die-level interconnect structures 106 may beelectrically coupled with the interconnect layer 102 c and configured toroute electrical signals between the die 102 and other electricaldevices. The electrical signals may include, for example, input/output(I/O) signals and/or power/ground signals that are used in connectionwith operation of the die 102.

In some embodiments, the package substrate 121 is an epoxy-basedlaminate substrate having a core and/or build-up layers such as, forexample, an Ajinomoto Build-up Film (ABF) substrate. The packagesubstrate 121 may include other suitable types of substrates in otherembodiments including, for example, substrates formed from glass,ceramic, or semiconductor materials.

The package substrate 121 may include electrical routing featuresconfigured to route electrical signals to or from the die 102. Theelectrical routing features may include, for example, pads or traces(not shown) disposed on one or more surfaces of the package substrate121 and/or internal routing features (not shown) such as, for example,trenches, vias or other interconnect structures to route electricalsignals through the package substrate 121. For example, in someembodiments, the package substrate 121 may include electrical routingfeatures such as pads (not shown) configured to receive the respectivedie-level interconnect structures 106 of the die 102.

The circuit board 122 may be a printed circuit board (PCB) composed ofan electrically insulative material such as an epoxy laminate. Forexample, the circuit board 122 may include electrically insulatinglayers composed of materials such as, for example,polytetrafluoroethylene, phenolic cotton paper materials such as FlameRetardant 4 (FR-4), FR-1, cotton paper and epoxy materials such as CEM-1or CEM-3, or woven glass materials that are laminated together using anepoxy resin prepreg material. Interconnect structures (not shown) suchas traces, trenches, or vias may be formed through the electricallyinsulating layers to route the electrical signals of the die 102 throughthe circuit board 122. The circuit board 122 may be composed of othersuitable materials in other embodiments. In some embodiments, thecircuit board 122 is a motherboard (e.g., motherboard 1002 of FIG. 6).

Package-level interconnects such as, for example, solder balls 112 maybe coupled to one or more pads (hereinafter “pads 110”) on the packagesubstrate 121 and/or on the circuit board 122 to form correspondingsolder joints that are configured to further route the electricalsignals between the package substrate 121 and the circuit board 122. Thepads 110 may be composed of any suitable electrically conductivematerial such as metal including, for example, nickel (Ni), palladium(Pd), gold (Au), silver (Ag), copper (Cu), and combinations thereof.Other suitable techniques to physically and/or electrically couple thepackage substrate 121 with the circuit board 122 may be used in otherembodiments.

The IC assembly 200 may include a wide variety of other suitableconfigurations in other embodiments including, for example, suitablecombinations of flip-chip and/or wire-bonding configurations,interposers, multi-chip package configurations includingsystem-in-package (SiP) and/or package-on-package (PoP) configurations.Other suitable techniques to route electrical signals between the die102 and other components of the IC assembly 200 may be used in someembodiments.

FIG. 3 schematically illustrates a cross-section side view of anintegrated circuit 300 including a non-planar gate thin film transistor1, in accordance with some embodiments. The non-planar (e.g., vertical)gate thin film transistor 1 may include a semiconductive layer 2 and agate dielectric layer 15 formed on a sidewall of one or more layersformed on a substrate 12. The one or more layers may include a firstelectrode 17 (e.g., a conductive layer), an inter-layer dielectric (ILD)18 formed on the first electrode, and a second electrode 16 (e.g.; aconductive layer) formed on the ILD 18. In some embodiments, firstelectrode 17 may be the source, and second electrode 16 may be thedrain. In other embodiments, first electrode 17 may be the drain, andsecond electrode 16 may be the source. A gate 13 may be formed incontact, e.g.; in direct contact, with the gate dielectric layer 15.

In some examples, the semiconductive layer 2 and a gate dielectric layer15 formed thereon may be disposed in a hole in the one or more layers.The gate 13 may be a conductive material filling the hole. Thesemiconductive layer 2 may wrap around the gate 13, e.g., surround thegate 13 on all sides of the hole. In some embodiments, thesemiconductive layer 2 may also be disposed in the hole below the gate13; however, this is not required. The wrap-around structure mayincrease the effective width (hence current drive and performance) ascompared to a planar gate thin film transistor where current flow may bethrough a rectangular sheet of charge. The integrated circuit 300 mayhave an improved lateral area to performance ratio as compared to anintegrated circuit based on a planar gate thin film transistor.

In some examples, the hole may have rounded sidewalls (the portion ofthe gate 13 filling the hole may have cylindrical sidewalls). FIG. 4,which will be described later in greater detail, illustrates a top viewof a hole 40 with rounded sidewalls in another example. Referring againto FIG. 3, current flow may be non-parallel (e.g., vertical, such asorthogonal to the substrate 12), and through a circular cross-section.This may be in contrast to a planar gate thin film transistor wherecurrent flow may be parallel to a substrate and through a rectangularsheet of charge. Current flow through a circular cross-section mayprovide a greater area of conduction (hence current drive andperformance). With a circular cross-section; I_(ON) of the non-planarthin film transistor 1 may be a product of a width of the gate 13 and afactor of Pi (π), which may provide faster charge storage than someplanar gate thin film transistors. I_(ON) refers to a threshold currentto flow through the channel region when the transistor is in an onstate. The width of the gate 13 refers to a thickness of the gate 13measured on an axis parallel to a surface of the substrate 12, in thisexample.

The gate 13 may be shared by more than one non-planar gate thin filmtransistor (e.g., transistors next to each other in a same plane mayshare a same gate). For example, the gate 13 may be shared by non-planargate thin film transistor 1 and another non-planar gate thin filmtransistor that is on another side of the hole and in a same planeparallel to a surface of the substrate 12. Also, in other examples, thegate 13 may be shared by non-planar gate thin film transistor 1 andanother non-planar gate thin film transistor on a same side of the holein a plane that is orthogonal to a surface of the substrate 12. Currentflow of each of more than one non-planar gate thin film transistor of ashared gate 13 may be through different regions of the gate 13. Thesharing of the gate 13 may be based on a characteristic of thin filmtransistors having a lower OFF state leakage than transistors formed ona substrate of semiconductor material. In some examples, sharedgate/accumulation may enable a higher I_(ON), which may be useful indriving loads faster in a memory application.

In some examples, at least one layer, e.g., an insulating layer 19, maybe between the substrate 12 and the one or more layers on the substrate12. In some examples, a wire (not shown, e.g., a wire for a word line)may be formed on the substrate 12, and the insulating layer 19 may beformed on the wire. In some examples, the hole may penetrate, e.g.,partially penetrate, the insulating layer 19, and the gate 13 in thehole may make contact with the wire for gate access from below thenon-planar gate thin film transistor 1. For gate access from above thenon-planar gate thin film transistor 1, a dielectric layer 14 may beformed on the one or more layers, and a contact of the gate 13 (forelectrical coupling to a wire) may be over a portion of the dielectriclayer 14.

The semiconductive layer 2 may be an amorphous semiconductor, apolycrystalline semiconductor, a chalcogenide, a semiconductive oxide,or the like, or combinations thereof. In some examples, thesemiconductive layer 2 may include thin channel transistor materialssuch as SnO₂, SnO, CoO, IGZO, ZnO, CuO, Cu₂O, ITO, IZO, NiO, InO, GaO,Ge (e.g., amorphous or polycrystalline), Si (e.g., amorphous orpolycrystalline), or the like, or combinations thereof.

In some examples, the semiconductive layer 2 may be doped with one ormore metals. Dopants may increase bandgap states and subsequentlyincrease the on state current. The dopant may be a metal dopant such asAs, InAs, Tl, Ta, Ti, Hf, Mn, MnCu, Cu, W, Pt, or the like, orcombinations thereof.

The first electrode 17, the second electrode 16, and the gate 13 may bemade from the same or different conductive material, e.g., the same ordifferent metal. In some examples, a plasma treatment may be applied tothe first electrode 17 and/or the second electrode 16 prior todeposition of the semiconductive layer 2. The plasma treatment may dopethe first electrode 17 and/or the second electrode 16, which may resultin a greater I_(ON) for the non-planar gate thin film transistor 1(which may be used in combination with a long channel length (Lg) thatmay provide low leakage and/or low I_(OFF)). I_(OFF) refers to currentthat flows through the channel region when the transistor is in an offstate. The gate dielectric layer 15, ILD 18, the insulating layer 19,and the dielectric layer 14 may be made from the same or differentdielectric materials.

The substrate 12 may be made from any material, including one or morenon-conductive or semiconductive materials as previously mentioned. Insome embodiments, as previously mentioned, substrate 12 may includeactive circuit devices (e.g., one or more active circuit devices formedin a silicon substrate, e.g., formed FEOL). The substrate 12 may form anactive layer (e.g., channel) of the active circuit devices that areformed in the substrate 12. In examples where the substrate 12 mayinclude active circuit devices, the insulating layer 19 may provideinsulation between the first electrode 17 and the active circuit devicesformed in the substrate 12. The active circuit devices formed insubstrate 12 may include one or more transistors, and the substrate 12may include a semiconductor material.

In some examples, non-planar gate thin film transistor 1 may correspondto a memory cell of a memory array, and the active circuit devicesformed in the substrate 12 may be part of peripheral circuitry of thememory array (e.g., circuitry of the memory array apart from the memorycells, including but not limited to sense/write circuitry). Therefore,the integrated circuits of memory cells of the memory array may beformed above (e.g., formed BEOL) the active circuit devices of theperipheral circuitry (which may be formed FEOL). This may be in contrastto some memory arrays where active circuit devices of the peripheralcircuitry are formed on a same planar substrate as active circuitdevices of the memory cells. Whereas array efficiency in some memoryarrays where active circuit devices of the peripheral circuitry areformed on a same planar substrate may not exceed 60%, the arrayefficiency of memory arrays disclosed herein may be greater than 60%,and in some cases may approach and/or reach 100%. Array efficiency maybe the ratio of area taken up by the memory array divided by the totalarea of the memory system (which includes the peripheral sensing anddriving circuitry, in addition to the array).

The non-planar gate thin film transistor 1 may enable a longer channellength (which may be based on the thickness of include ILD 18 and/or adistance between the first electrode 17 and the second electrode 16) fora given substrate layout size than planar gate thin film transistors.The longer channel may result in lower leakage (e.g., lower I_(OFT)).Due to the lower leakage, the non-planar gate thin film transistor 1 maybe more suited (than some planar gate thin film transistors) for use ina memory cell in a DRAM (dynamic random access memory) array. Inparticular, besides improved performance, power savings may be realizedif the non-planar gate thin film transistor 1 is utilized for a volatilememory cell (e.g., due to the lower leakage, a refresh rate of thevolatile memory may be lower). In some temporary data storageapplications, such as caching, the lower leakage current may enablerefreshing to be bypassed entirely.

Some GAA (gate all around) structures include an ungated region of asemiconductor (a region where the gate does not wrap around thesemiconductor). In contrast to these GAA structures, the semiconductivelayer 2 may wrap around the gate 13, and the semiconductive material 2is in contact, e.g., direct contact, with an entire gate portion betweenthe first and second electrodes 16 and 17. Therefore, the non-planarthin film transistor 1 may not include an ungated region, which mayimprove the off state leakage of the transistors.

FIG. 4 schematically illustrates a top view of the hole 40, a firstelectrode 37, and a second electrode 36, for an integrated circuitincluding a non-planar gate thin film transistor, in accordance withsome embodiments. In some embodiments, the first electrode 37 maycorrespond to the first electrode 17 shown in FIG. 3, and the secondelectrode 36 may correspond to the second electrode 16 shown in FIG. 3.The hole 40 may correspond to the hole described with respect to FIG. 3(e.g., in which the semiconductive material 2, gate dielectric 15, andgate 13 are formed). The semiconductive material 41 may correspond tothe semiconductive material 2 shown in FIG. 3 and the gate 43 maycorrespond to the gate 13 shown in FIG. 3.

As shown in FIG. 4, only a portion of the second electrode 36 may beformed over the first electrode 37 in this example. For example, asshown in FIG. 4, the long axes of the source and drain may be orientedabout ninety degrees with respect to one another and a portion of thesource may overlap with a portion of the drain. In some examples, a samemask used to form the first electrode 37 may be rotated ninety degreesrelative to the substrate and used for the second electrode 36, whichmay minimize masks/costs.

The hole 40 may be formed in this overlapping portion of the secondelectrode 36 and the first electrode 37. In this example, agate/source/drain definition may be self-aligned (e.g., the mask thatdefines any two orthogonal lines (interconnects/wires), by the way oforthogonality, is self-aligned). Self-alignment may simplify processingsteps and may require minimal masks. In examples where the substrate(FIG. 3) includes peripheral circuitry, the most difficult patterningprocesses associated with the most critical dimensions may be associatedwith the peripheral circuitry, and in silicon. In other examples, anentire portion of a first electrode 37 may be above a second electrode36.

FIGS. 5-8 schematically illustrate cross-section side views of theformation of an integrated circuit that utilizes the hole, source, anddrain of FIG. 4, in accordance with some embodiments, Referring to FIG.5, an insulating layer 39 may be deposited on a substrate 30 having aplanar surface. A first electrode 37 may be patterned and formed on theinsulating layer 39. In some embodiments, a bit line wire (not shown) incontact with the first electrode 37 may also be patterned. An ILD 38 maybe deposited on the first electrode 37.

Referring to FIG. 6, the second electrode 36 may be patterned. A bitline wire (not shown) in contact with the second electrode 36 may alsobe patterned and formed on the ILD 38. A dielectric 35 that may bedeposited on the ILD 38 for formation of the second electrode 36 (e.g.,in the dielectric 35) is shown. A dielectric layer 34 may be depositedon the second electrode 36 and the dielectric 35 after formation of thesecond electrode 36.

Referring to FIG. 7, a hole 40 may be formed (e.g., by dry etch and/orwet etch) through the dielectric layer 34, the second electrode 36, theILD 38, and the first electrode 37. The hole 40 may extend into theinsulating layer 39 (e.g., below the surface of the insulating layer 39but above the surface of the substrate 30), Dry etch may be used in anyexample, including where the hole 40 exposes a gate access wire (notshown) formed on the substrate 30 prior to formation of the hole 40. Wetetch may be used in any example, such as in examples where a contactstructure may be formed at the bottom of the hole 40.

Referring to FIG. 8, a semiconductive layer 41 may be deposited on asidewall of the hole 40 (FIG. 7). Depending on the aspect ratio, atomiclayer deposition, chemical vapor deposition, physical vapor deposition,evaporation, sputtering, or the like, or combinations thereof, may beused. The semiconductive layer 41 may also be deposited on at least aportion of the top surface of the dielectric layer 34. A gate dielectriclayer 45 may be deposited on the semiconductive layer 41. The dielectricmaterial may be HfO₂, TiO₂, Ta₂O₅, SiO₇, SiN, or the like, orcombinations thereof. The dielectric material may be deposited usingatomic layer deposition, chemical vapor deposition, physical vapordeposition, sputtering, or the like, or combinations thereof.

After the deposition of the gate dielectric layer 45, the hole 40 (FIG.7) may be filled with a conductive material to form the gate 43. Forexample, the gate dielectric layer 45 may cover the semiconductive layer41 in the hole 40. In some examples, conductive material deposited abovethe dielectric layer 34 may be patterned to form the contact 49 for agate access wire. For example, the contact 49 may extend laterally pastthe boundary of the hole 40.

FIG. 9 is a flow diagram that illustrates a process for forming anintegrated circuit including a non-planar gate thin film transistor, inaccordance with some embodiments.

In block 901, a first electrode may be formed above a substrate. Inblock 902, an ILD may be formed above the first electrode. In block 903,a second electrode may be formed above the ILD, At least a portion ofthe second electrode may be formed over the first electrode.

In block 904, a hole may be formed in the portion of the secondelectrode, and the hole may extend through the second electrode and thefirst electrode. In block 905, a semiconductive layer may be formed on asidewall of the hole. In block 906, a gate dielectric layer may bedisposed in the hole and formed on the semiconductive layer. In block907, a gate disposed in the hole may be formed after the formation ofthe gate dielectric layer.

FIG. 10 schematically illustrates a cross-section side view of anon-planar gate thin film transistor based integrated circuit 950 in aconfiguration for a programmable drive, in accordance with someembodiments. The integrated circuit 950 may include a count of N one ormore drains and a count of k one or more sources. In the illustratedexample, the N and k are both equal to two (a first electrode 937 and asecond electrode 936 corresponding to source, and drain₁, and a firstelectrode 957 and a second electrode 956 corresponding to source_(s) anddrain_(N)), although in other examples N and k may be different valuesand/or may range from one to twenty or more.

In one example, any two of electrodes 936, 937, 956, and 957 can beselected to be the respective source/drain of a transistor (e.g., basedon access needs). In some examples, the selection may be madedynamically by a control circuit. Non-selected ones of the electrodes936, 937, 956, and 957 may be disconnected from a read/write circuitry,and/or may be held at a lower voltage, (e.g., floated). Depending onwhich drain/source is selected, a different channel length, andaccordingly a different I_(ON) may be utilized for the correspondingtransistor. In other examples, the selection may be hard-wired duringmanufacturing.

In some examples, more than one source may be simultaneously selected toprovide a lower contact resistance. For instance, referring to FIG. 10,more than one of the electrodes 936 and 956 may be selected and/or morethan one of the electrodes 937 and 957 may be selected.

FIG. 11 schematically illustrates an example system (e.g., computingdevice 1000) that may include an IC device including a non-planar gatethin film transistor (e.g., non-planar gate thin film transistor 300and/or a non-planar gate thin film transistor formed using the process900 or some other process described herein with reference to FIGS. 3-10.Components of the computing device 1000 may be housed in an enclosure(e.g., housing 1008). The motherboard 1002 may include a number ofcomponents, including but not limited to a processor 1004 and at leastone communication chip 1006. The processor 1004 may be physically andelectrically coupled to the motherboard 1002. In some implementations,the at least one communication chip 1006 may also be physically andelectrically coupled to the motherboard 1002. In furtherimplementations, the communication chip 1006 may be part of theprocessor 1004.

Depending on its applications, computing device 1000 may include othercomponents that may or may not be physically and electrically coupled tothe motherboard 1002. These other components may include, but are notlimited to, volatile memory (e.g., DRAM), non-volatile memory (e.g.,ROM), flash memory, a graphics processor, a digital signal processor, acrypto processor, a chipset, an antenna, a display, a touchscreendisplay, a touchscreen controller, a battery, an audio codec, a videocodec, a power amplifier, a global positioning system (GPS) device, acompass, a Geiger counter, an accelerometer, a gyroscope, a speaker, acamera, and a mass storage device (such as hard disk drive, compact disk(CD), digital versatile disk (DVD), and so forth).

The communication chip 1006 may enable wireless communications for thetransfer of data to and from the computing device 1000. The term“wireless” and its derivatives may be used to describe circuits,devices, systems, methods, techniques, communications channels, etc.,that may communicate data through the use of modulated electromagneticradiation through a non-solid medium. The term does not imply that theassociated devices do not contain any wires, although in someembodiments they might not. The communication chip 1006 may implementany of a number of wireless standards or protocols, including but notlimited to Institute for Electrical and Electronic Engineers (IEEE)standards including Wi-Fi (IEEE 802.11 family), IEEE 802.16 standards(e.g., IEEE 802.16-2005 Amendment), Long-Term Evolution (LTE) projectalong with any amendments, updates, and/or revisions (e.g., advanced LTEproject, ultra mobile broadband (UMB) project (also referred to as“3GPP2”), etc.). IEEE 802.16 compatible broadband wireless access (BWA)networks are generally referred to as WiMAX networks, an acronym thatstands for Worldwide Interoperability for Microwave Access, which is acertification mark for products that pass conformity andinteroperability tests for the IEEE 802.16 standards. The communicationchip 1006 may operate in accordance with a Global System for MobileCommunication (GSM), General Packet Radio Service (CPRS), UniversalMobile Telecommunications System (UMTS), High Speed Packet Access(HSPA), Evolved HSPA (E-HSPA), or LTE network. The communication chip1006 may operate in accordance with Enhanced Data for GSM Evolution(EDGE), GSM EDGE Radio Access Network (GERAN), Universal TerrestrialRadio Access Network (UTRAN), or Evolved UTRAN (E-UTRAN). Thecommunication chip 1006 may operate in accordance with Code DivisionMultiple Access (CDMA), Time Division Multiple Access (TDMA), DigitalEnhanced Cordless Telecommunications (DECT), Evolution-Data Optimized(EV-DO), derivatives thereof, as well as any other wireless protocolsthat are designated as 3G, 4G, 5G, and beyond. The communication chip1006 may operate in accordance with other wireless protocols in otherembodiments.

The computing device 1000 may include a plurality of communication chips1006. For instance, a first communication chip 1006 may be dedicated toshorter range wireless communications such as Wi-Fi and Bluetooth and asecond communication chip 1006 may be dedicated to longer range wirelesscommunications such as GPS, EDGE, GPRS, CDMA, WiMAX, LTE, EV-DO, andothers.

The processor 1004 and/or any memory of the computing device 1000 mayinclude a die (e.g., die 102 of FIG. 1 and FIG. 2) including the ICand/or non-planar gate thin film transistor described herein (e.g.,non-planar gate thin film transistor 1, IC 300, and/or a non-planar gatethin film transistor using the process 900 or any process describedherein with reference to FIGS. 3-10) as described herein. In someexamples, a cache (not shown) of the processor 1004 may include a die(e.g., die 102 of FIG. 1 and FIG. 2) including the IC and/or non-planargate thin film transistor described herein. In some embodiments, the dieof the processor 1004 may further include active circuit devices formedFEOL in a substrate, and the non-planar gate thin film transistorsdescribed herein may be formed BEOL above the FEOL devices. In someembodiments, the die 102 of FIG. 2 may be mounted in a package assembly(e.g., package assembly 200) that is mounted on a circuit board such asthe motherboard 1002, The term “processor” may refer to any device orportion of a device that processes electronic data from registers and/ormemory to transform that electronic data into other electronic data thatmay be stored in registers and/or memory.

The communication chip 1006 may also include a die (e.g., die 102)including the IC and/or non-planar gate thin film transistor describedherein (e.g., non-planar gate thin film transistor 1, IC 300 and/or anon-planar gate thin film transistor using the process 900 or anyprocess described herein with reference to FIGS. 3-10) as describedherein. In some embodiments, the die of the communication chip 1006 mayfurther include active circuit devices formed FEOL in a substrate, andthe non-planar gate thin film transistors described herein may be formedBEOL above the FEOL devices. In further implementations, anothercomponent (e.g., memory device or other integrated circuit device)housed within the computing device 1000 may contain a die (e.g., die102) including the IC and/or non-planar gate thin film transistordescribed herein (e.g., non-planar gate thin film transistor 1, IC 300,and/or a non-planar gate thin film transistor using the process 900 orany process described herein with reference to FIGS. 3-10) as describedherein.

In various implementations, the computing device 1000 may be a mobilecomputing device, a laptop, a netbook, a notebook, an ultrabook, asmartphone, a tablet, a personal digital assistant (PDA), an ultramobile PC, a mobile phone, a desktop computer, a server, a printer, ascanner, a monitor, a set-top box, an entertainment control unit, adigital camera, a portable music player, or a digital video recorder. Infurther implementations, the computing device 1000 may be any otherelectronic device that processes data.

Some non-limiting examples of various embodiments are provided below.

Example 1 is an integrated circuit, comprising: a plurality of layersformed on a substrate, the plurality of layers including a first one ofa source or drain, an inter-layer dielectric (ILD) formed on the firstone of the source or drain, and a second one of the source or drainformed on the ILD; a semiconductive layer formed on a sidewall of theplurality of layers; a gate dielectric layer formed on thesemiconductive layer; and a gate formed in contact with the gatedielectric layer.

Example 2 may include the subject matter of example 1, and the sidewallof the plurality of layers comprises a sidewall of a hole formed in theplurality of layers.

Example 3 may include the subject matter of any of examples 1-2, and thegate dielectric layer and the gate are disposed in the hole, and whereinthe semiconductive layer formed on the sidewall of the hole surrounds aside surface of the gate.

Example 4 may include the subject matter of any of examples 1-3, and thesidewall of the hole is rounded.

Example 5 may include the subject matter of any of examples 1-4, and thesemiconductive layer comprises at least one of an amorphoussemiconductor, a polycrystalline semiconductor, a chalcogenide, or asemiconductive oxide.

Example 6 may include the subject matter of any of examples 1-5, and thesemiconductive material comprises at least one of SnO₂, SnO, CoO, IGZO,ZnO, CuO, Cu₂O, ITO, IZO, NiO, InO, GaO, Ge or Si.

Example 7 may include the subject matter of any of examples 1-6, and thesemiconductive layer is doped with one or more metals,

Example 8 may include the subject matter of any of examples 1-7, andonly a portion of the second one of the source or drain is formed overthe first one of the source or drain in the plurality of layers.

Example 9 may include the subject matter of any of examples 1-8, and atleast one of the source or drain is doped.

Example 10 may include the subject matter of any of examples 1-10, andthe substrate comprises peripheral circuitry.

Example 11 is an integrated circuit, comprising: a substrate; and afirst one of a source or drain formed above the substrate; a second oneof the source or drain formed above the first one of the source ordrain; and a hole formed through the first one of the source or drainand the second one of the source or drain; and a semiconductive layerformed on a sidewall of the hole.

Example 12 may include the subject matter of example 11, and thesemiconductive layer comprises a shared channel layer for a plurality oftransistors.

Example 13 may include the subject matter of any of examples 11-12, andthe semiconductive layer comprises at least one of an amorphoussemiconductor, a polycrystalline semiconductor, a chalcogenide, or asemiconductive oxide.

Example 14 may include the subject matter of any of examples 11-13, andthe first one of the source or drain is formed on a different source ordrain, and a second one of the different source or drain is formed onthe other one of the different source or drain.

Example 15 may include the subject matter of any of examples 11-14, andthe semiconductive layer is orthogonal to a planar surface of thesubstrate.

Example 16 is a system, comprising: a processor; and at least one of anetwork device; a display, or a memory coupled to the processor; whereinthe processor includes an integrated circuited circuit, the integratedcircuit including: a plurality of layers formed on a substrate; theplurality of layers including a first one of a source or drain, aninter-layer dielectric (ILD) formed on the first one of the source ordrain; and a second one of the source or drain formed on the ILD; asemiconductive layer formed on a sidewall of the plurality of layers;and a gate dielectric layer formed on the semiconductive layer; and agate formed in contact with the gate dielectric layer.

Example 17 may include the subject matter of example 16, and at leastone of the source or drain is doped.

Example 18 may include the subject matter of any of examples 16-17, andthe substrate comprises peripheral circuitry,

Example 19 may include the subject matter of any of examples 16-18, andonly a portion of the second one of the source or drain is formed overthe first one of the source or drain in the plurality of layers.

Example 20 may include the subject matter of any of examples 16-19, andthe semiconductive layer comprises at least one of an amorphoussemiconductor; a polycrystalline semiconductor; a chalcogenide, or asemiconductive oxide.

Example 21 is a method of producing an integrated circuit, the methodcomprising: forming a first one of a source or drain above a substrate;forming an inter-layer dielectric (ILD) above the first one of thesource or drain; forming a second one of the source or drain above theILD, wherein at least a portion of the second one of the source or drainis formed over the first one of the source or drain; forming a hole inthe portion of the second one of the source or drain; forming asemiconductive layer on a sidewall of the hole; forming a gatedielectric layer disposed in the hole and on the semiconductive layer;and forming a gate disposed in the hole after the formation of the gatedielectric layer.

Example 22 may include the subject matter of example 21, and a sidewallof the hole is circular.

Example 23 may include the subject matter of any of examples 21-22, andforming the gate in the hole after formation of the gate dielectriclayer further comprises filling the hole with conductor.

Example 24 may include the subject matter of any of examples 21-23, andthe semiconductive layer comprises at least one of an amorphoussemiconductor, a polycrystalline semiconductor, a chalcogenide, or asemiconductive oxide.

Example 25 may include the subject matter of any of examples 21-24, andforming FEOL (front-end-of-line) circuitry, wherein the substratecomprises said FEOL circuitry; wherein forming the first one of thesource or drain, the ILD, the second one of the source or drain, and thehole comprises only BEOL (back-end-of-line) processes.

Various embodiments may include any suitable combination of theabove-described embodiments including alternative (or) embodiments ofembodiments that are described in conjunctive form (and) above (e.g.,the “and” may be “and/or”). Furthermore, some embodiments may includeone or more articles of manufacture (e.g., non-transitorycomputer-readable media) having instructions, stored thereon, that whenexecuted result in actions of any of the above-described embodiments.Moreover, some embodiments may include apparatuses or systems having anysuitable means for carrying out the various operations of theabove-described embodiments.

The above description of illustrated implementations, including what isdescribed in the Abstract, is not intended to be exhaustive or to limitthe embodiments of the present disclosure to the precise formsdisclosed. While specific implementations and examples are describedherein for illustrative purposes, various equivalent modifications arepossible within the scope of the present disclosure, as those skilled inthe relevant art will recognize.

These modifications may be made to embodiments of the present disclosurein light of the above detailed description. The terms used in thefollowing claims should not be construed to limit various embodiments ofthe present disclosure to the specific implementations disclosed in thespecification and the claims. Rather, the scope is to be determinedentirely by the following claims, which are to be construed inaccordance with established doctrines of claim interpretation.

What is claimed is:
 1. An integrated circuit, comprising: a plurality oflayers formed on a substrate, the plurality of layers including a firstone of a source or drain, an inter-layer dielectric (ILD) formed on thefirst one of the source or drain, and a second one of the source ordrain formed on the ILD; a semiconductive layer formed on a sidewall ofthe plurality of layers; a gate dielectric layer formed on thesemiconductive layer; and a gate formed in contact with the gatedielectric layer.
 2. The integrated circuit of claim 1, wherein thesidewall of the plurality of layers comprises a sidewall of a holeformed in the plurality of layers.
 3. The integrated circuit of claim 1,wherein the gate dielectric layer and the gate are disposed in the hole,and wherein the semiconductive layer formed on the sidewall of the holesurrounds a side surface of the gate.
 4. The integrated circuit of claim2, wherein the sidewall of the hole is rounded.
 5. The integratedcircuit of claim 1, wherein the semiconductive layer comprises at leastone of an amorphous semiconductor, a polycrystalline semiconductor, achalcogenide, or a semiconductive oxide.
 6. The integrated circuit ofclaim 1, wherein the semiconductive material comprises at least one ofSnO₂, SnO, CoO, IGZO, ZnO, CuO, Cu₂O, ITO, IZO, NiO, InO, GaO, Ge or Si.7. The integrated circuit of claim 1, wherein the semiconductive layeris doped with one or more metals.
 8. The integrated circuit of claim 1,wherein only a portion of the second one of the source or drain isformed over the first one of the source or drain in the plurality oflayers.
 9. The integrated circuit of claim 1, wherein at least one ofthe source or drain is doped.
 10. The integrated circuit of claim 1,wherein the substrate comprises peripheral circuitry.
 11. An integratedcircuit, comprising: a substrate; and a first one of a source or drainformed above the substrate; a second one of the source or drain formedabove the first one of the source or drain; and a hole formed throughthe first one of the source or drain and the second one of the source ordrain; and a semiconductive layer formed on a sidewall of the hole. 12.The integrated circuit of claim 11, wherein the semiconductive layercomprises a shared channel layer for a plurality of transistors.
 13. Theintegrated circuit of claim 11, wherein the semiconductive layercomprises at least one of an amorphous semiconductor, a polycrystallinesemiconductor, a chalcogenide, or a semiconductive oxide.
 14. Theintegrated circuit of claim 11, wherein the first one of the source ordrain is formed on a different source or drain, and a second one of thedifferent source or drain is formed on the other one of the differentsource or drain.
 15. The integrated circuit of claim 1, wherein thesemiconductive layer is orthogonal to a planar surface of the substrate.16. A system, comprising: a processor; and at least one of a networkdevice, a display, or a memory coupled to the processor; wherein theprocessor includes an integrated circuited circuit, the integratedcircuit including: a plurality of layers formed on a substrate, theplurality of layers including a first one of a source or drain, aninter-layer dielectric (ILD) formed on the first one of the source ordrain, and a second one of the source or drain formed on the ILD; asemiconductive layer formed on a sidewall of the plurality of layers;and a gate dielectric layer formed on the semiconductive layer; and agate formed in contact with the gate dielectric layer.
 17. The system ofclaim 16, wherein at least one of the source or drain is doped.
 18. Thesystem of claim 16, wherein the substrate comprises peripheralcircuitry.
 19. The system of claim 16, wherein only a portion of thesecond one of the source or drain is formed over the first one of thesource or drain in the plurality of layers.
 20. The system of claim 16,wherein the semiconductive layer comprises at least one of an amorphoussemiconductor, a polycrystalline semiconductor, a chalcogenide, or asemiconductive oxide.
 21. A method of producing an integrated circuit,the method comprising: forming a first one of a source or drain above asubstrate; forming an inter-layer dielectric (ILD) above the first oneof the source or drain; forming a second one of the source or drainabove the ILD, wherein at least a portion of the second one of thesource or drain is formed over the first one of the source or drain;forming a hole in the portion of the second one of the source or drain;forming a semiconductive layer on a sidewall of the hole; forming a gatedielectric layer disposed in the hole and on the semiconductive layer;and forming a gate disposed in the hole after the formation of the gatedielectric layer.
 22. The method of claim 21, wherein a sidewall of thehole is circular.
 23. The method of claim 22, wherein forming the gatein the hole after formation of the gate dielectric layer furthercomprises filling the hole with conductor.
 24. The method of claim 21,wherein the semiconductive layer comprises at least one of an amorphoussemiconductor, a polycrystalline semiconductor, a chalcogenide, or asemiconductive oxide.
 25. The method of claim 21, further comprising:forming FEOL (front-end-of-line) circuitry, wherein the substratecomprises said FEOL circuitry; wherein forming the first one of thesource or drain, the ILD, the second one of the source or drain, and thehole comprises only BEOL (back-end-of-line) processes.